Find a BMW CCA auto cross event and just go the way that your car is now. See what the other guys there are using. If you have never done any auto crossing or track driving I am sure that the weak link is the driver not the car. You will learn more, faster and safer on a car with lower limits. The smooth predictable power of your n/a six will help you.

The best mod you can do is improve the driver. On a closed course a good driver can significantly close the gap created by a power advantage.

If you start getting good in your class and you want 'race rubber' you'll probably end up with a second set of wheels and some hoosiers or something like that.

for a natural apirated engine like one on your car, I would suggest supercharger... I am no expert but Ive heard tremendous gains on HP. but yes they are expensive. so it depends on your budget. how much were you thnking of spend and do you want your mod to e exclusively on performance? I do think that there should be a room for a improvement on your engine... i dont know how much though. then there are transmission and tires to think of... so yea, it can be a bit of a dough but I am pretty sure it can be done.

Nothing. Its slow. It will always be slow. Dont waste your time or money.

Oh, and use the search button.

LOL! If you want chips, head to the grocery store. If you want tunes, check out the power box (not sure if it's for the 325 though). And yea, it's a waste of money.

If you want to make your car faster.....head to the track and do a NASA sponsored HPDE event. The best way to make you and your car faster is to drive with a professional instructor. Without a good driver, even the fasted car in the world can get passed by a 325. (well that is pushing it but you get the drift)

LOL! If you want chips, head to the grocery store. If you want tunes, check out the power box (not sure if it's for the 325 though). And yea, it's a waste of money.

If you want to make your car faster.....head to the track and do a NASA sponsored HPDE event. The best way to make you and your car faster is to drive with a professional instructor. Without a good driver, even the fasted car in the world can get passed by a 325. (well that is pushing it but you get the drift)

+1
there was a video on the internet a while back where a female Pro-driver was lapping amateur drivers while driving a mini-van. wish I could find that again.

sinces those guys are no help...
get a charcoal delete,
k&n drop in (if you dont want to get a intake),
and AAtune
its probably the most you could do to a 325(same as 328 330)
335 is cool to drive but dealer visits are often